Square & Cube Root Tests — Pick a Level and Start
Tap a level to see every test in it. Start at Level 1 the day you finish the digit tricks, then move to Level 2 with the timer running to push accuracy under pressure.
Level 1 Basic Checking… View tests
One idea applied cleanly — root a four-digit perfect square from its last digit, place the point in a decimal root, take the cube root of a negative number, add the least number that reaches the next square, and count the perfect squares in a range. Attempt these without the clock while the digit tricks are still settling.
Level 2 Tier I Standard Checking… View tests
Real SSC CGL Tier I difficulty — two ideas chained in one question: a remainder removed before the root is taken, bounds that are themselves radicals and must be simplified before counting, a missing digit that then has to be cubed, a nested radical equation, and the multiplier for a cube set against the divisor for a square. This is the score that tells you the chapter is exam-ready.
Square and cube root is the fastest scoring chapter in SSC CGL Quantitative Aptitude, and the one where the gap between a prepared and an unprepared candidate is most visible. Someone who knows the digit tricks reads √4489 in about six seconds; someone who reaches for long division spends ninety and can still slip. Nearly every shift carries a question that belongs to this chapter outright — a direct root, a least number to add or subtract, or a counting question — and the same skills decide how quickly you move through simplification, surds and indices, and mensuration.
These practice tests put twenty-five such questions in front of you in one sitting, which is what turns the last-digit table from something you can recite into something you apply without thinking. Every question comes with a full solution and the shortcut, in English or Hindi.
How Many Square and Cube Root Questions Are Asked in SSC CGL?
The chapter usually gets one to two direct questions, and its methods are reused inside simplification, surds and indices, and anywhere a root has to be taken at speed.
| Chapter | Tier I (out of 25) | Tier II Paper I (out of 30) |
|---|---|---|
| Square & Cube Roots | 1–2 | 1–2 |
| Simplification, Surds & Indices | 1–2 | 2–3 |
| Number System | 2–3 | 3–4 |
| LCM & HCF | 1–2 | 1–2 |
| Decimal & Fraction | 1–2 | 1–2 |
Typical spread across recent SSC CGL shifts. SSC does not publish a chapter-wise breakup, so treat these as planning ranges. Tier I maths is always 25 questions in a locked 15-minute section.
What You Will Practice in the Square & Cube Root Chapter
Core topics
- Square roots of four-, five- and eight-digit perfect squares by the last-digit and decade method
- Square roots of decimals, fractions, mixed numbers and powers of ten
- Repeating-digit patterns — 112 = 121, 1112 = 12321, 33332 = 11108889
- The identities n2 + n + (n + 1) = (n + 1)2, n(n + 2) + 1 = (n + 1)2 and a2 − b2 = (a + b)(a − b)
- Digit-count rules for square roots and cube roots, forwards and backwards
- Cubes and cube roots — negatives, decimals, fractions and mixed expressions
- Chains of cube roots, mixed-index radicals and radicals written as fractional powers
- The missing digit that makes a number a perfect square or cube
- Least number to add, subtract, multiply or divide to reach a perfect square or cube
- Greatest and least n-digit perfect squares and cubes
- Counting problems — squares in a range, naturals between consecutive squares, non-squares, sixth powers, and integers trapped between radical bounds
- Word problems that reduce to a square — equal contributions, rupees and paise, rows and columns, and arrangements with a remainder
Squares you should know on sight
| n | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
|---|---|---|---|---|---|---|---|---|---|---|
| n2 | 121 | 144 | 169 | 196 | 225 | 256 | 289 | 324 | 361 | 400 |
| n | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 |
| n2 | 441 | 484 | 529 | 576 | 625 | 676 | 729 | 784 | 841 | 900 |
Keep the round anchors with them — 402 = 1600, 502 = 2500, 602 = 3600, 702 = 4900, 802 = 6400, 902 = 8100 — because those place a root inside the right decade.
The last-digit rule for squares
| Root ends in | 1 or 9 | 2 or 8 | 3 or 7 | 4 or 6 | 5 | 0 |
|---|---|---|---|---|---|---|
| Square ends in | 1 | 4 | 9 | 6 | 5 | 0 |
Every ending comes from a pair of digits, so the last digit narrows the root to two candidates and the decade picks between them. A number ending in 2, 3, 7 or 8 is never a perfect square; a square ending in 5 must end in 25; and a perfect square always ends in an even number of zeros.
Cubes, and why cube roots are easier
| n | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n3 | 1 | 8 | 27 | 64 | 125 | 216 | 343 | 512 | 729 | 1000 | 1331 | 1728 |
| Cube ends in | 1 | 8 | 7 | 4 | 5 | 6 | 3 | 2 | 9 | 0 | 1 | 8 |
The last digit of a cube identifies the last digit of its root uniquely — only 2, 3, 7 and 8 swap places, and the rest map to themselves. So for any perfect cube up to six digits: strike off the last three digits and the block that remains sits between two cubes, whose smaller root is the ten digit; the last digit of the number then gives the unit digit. ∛262144 → 262 lies between 216 and 343, so the ten digit is 6, and the number ends in 4, so the root is 64.
Decimals, and the one rule that covers them
| Radical | Decimal places go | Example |
|---|---|---|
| Square root | ÷ 2 | √0.00000841 = 0.0029 (8 places → 4) |
| Cube root | ÷ 3 | ∛0.000216 = 0.06 (6 places → 2) |
| Fourth root | ÷ 4 | 4√0.0016 = 0.2 (4 places → 1) |
The digits of the root never change — only the point moves. Given √0.5776 = 0.76, it follows at once that √57.76 = 7.6 and √0.005776 = 0.076, with no fresh working.
Add, subtract, multiply or divide — the four cousins
| Asked for | Method | Example |
|---|---|---|
| Least number to add | (k + 1)2 − N | 3455 → 3481 − 3455 = 26 |
| Least number to subtract | N − k2 | 8000 → 8000 − 7921 = 79 |
| Least multiplier for a square | Product of the primes with an odd count | 4500 = 22×32×53 → 5 |
| Least divisor for a cube | Divide out the surplus above a multiple of 3 | 1944 = 23×35 → 9 |
The add and subtract answers always sum to (k + 1)2 − k2 = 2k + 1, which makes a quick check. Cubes use the same layout with k3 and (k + 1)3.
Also worth memorising
- A number with 2n or 2n − 1 digits has a square root with n digits; group in threes from the right for cube roots
- Exactly 2n natural numbers lie between n2 and (n + 1)2, and none of them is a square
- Both a perfect square and a perfect cube means a sixth power k6 — 1, 64, 729, 4096, 15625
- (10n + 5)2 = n(n + 1) followed by 25 — so 2352 = 55225, and read backwards, √55225 = 235
- Greatest 2n-digit perfect square has a root made of n nines: 9992 = 998001
- a < √N < b means a2 < N < b2; a < ∛N < b means a3 < N < b3
- ∛(−a) = −∛a — a cube root keeps the sign, a square root does not
Square & Cube Root Chapter Notes
Every rule on this page is worked out in full in the chapter notes — the digit tables, the decimal-point rules, the four add-subtract-multiply-divide types, the counting shortcuts and the traps that cost marks, with examples throughout. Read the notes first if the chapter is new to you, then come back and attempt Level 1.
Solved Examples — SSC CGL Square & Cube Root
How the Square & Cube Root Chapter Tests Work
- 25 questions per test, with a full question palette — answered, skipped, marked for review, not visited.
- Optional 30-minute timer — with the clock to build exam speed, without it while you are still learning the tricks.
- Marking: +2 correct, −0.5 wrong, 0 unattempted — the same scheme as the real paper.
- Solutions, shortcut tricks and concept notes open after you submit, question by question.
- English and हिंदी, chosen at the start of every test.
- Free with a TrickySSC account — sign in once with Google or your mobile number, and every test is open to you.
How to Prepare Square & Cube Root for SSC CGL
- Learn squares to 30 and cubes to 12 first. Everything in the chapter is built on them, and no trick works without them.
- Drill the last-digit table until it is reflex. The last digit narrows a square root to two candidates; the decade decides. That is the whole method for four- and five-digit roots.
- Fix the decimal rule in one line: halve the places for a square root, divide by three for a cube root, by four for a fourth root. Mixing these up shifts the answer by a factor of ten and lands you on a distractor.
- Never forget the sign on a cube root. ∛(−5832) = −18. This single slip costs more marks in this chapter than anything else.
- Practise factorisation for the multiply and divide types. Squares need every exponent even; cubes need every exponent to reach a multiple of three.
- Read the last line of the question again. One stem can contain the number added, the square reached and its root — and only one of them is the answer.
- Do Level 1 untimed, the same day you finish the tricks. The aim is correct recall, not speed.
- Move to Level 2 with the 30-minute clock on. Then verify against a previous year paper and a full mock test under locked sectional timing.
SSC CGL वर्ग, वर्गमूल एवं घन, घनमूल चैप्टर टेस्ट — हिंदी में
वर्ग और घनमूल SSC CGL गणित का सबसे तेज़ अंक देने वाला अध्याय है। लगभग हर शिफ्ट में इसका 1–2 प्रश्न सीधे आता है — जैसे किसी पूर्ण वर्ग का मूल, पूर्ण वर्ग बनाने के लिए जोड़ी या घटाई जाने वाली न्यूनतम संख्या, या किसी परिसर में वर्गों की गिनती — और यही कौशल सरलीकरण, करणी-घातांक तथा क्षेत्रमिति में भी काम आता है।
TrickySSC पर इस अध्याय के सभी टेस्ट हिंदी में उपलब्ध हैं — प्रश्न, विकल्प, विस्तृत हल और शॉर्टकट ट्रिक सब हिंदी में। दो स्तर हैं: लेवल 1 (आधारभूत) और लेवल 2 (टियर I स्तर)। प्रत्येक टेस्ट में 25 प्रश्न, वैकल्पिक 30 मिनट का टाइमर और +2 / −0.5 की वही मार्किंग जो असली परीक्षा में होती है।
याद रखने योग्य नियम: संख्या का अंतिम अंक मूल का इकाई अंक दो विकल्पों तक सीमित कर देता है और दहाई का वर्ग उनमें से एक चुन लेता है; दशमलव में वर्गमूल लेने पर दशमलव स्थान आधे और घनमूल लेने पर तीन से भाग हो जाते हैं; और ऋणात्मक संख्या का घनमूल ऋणात्मक होता है — ∛(−5832) = −18। पूरे नियम हिंदी नोट्स में विस्तार से दिए गए हैं।