Divisibility and factors — Quantitative aptitude for kids
Does 4,536 divide by 9? Add its digits: 4 + 5 + 3 + 6 = 18, which divides by 9, so yes! Divisibility rules let you test a number without long division. Prime powers tell you how many factors a number has, and the remainder tells you what to add or take away.
Rules and powers — “divisibility rules test a number quickly; prime powers count its factors”
By 3 or 9: the digit sum divides by 3 or 9. By 4: the last two digits. By 8: the last three digits. By 6: even and divisible by 3. By 11: the sums of alternate digits are equal or differ by 11.
Number of factors: write n = p^a × q^b …, then the count is (a + 1) × (b + 1) × ….
To make n divisible by d: divide, then add (d − remainder) or take away the remainder.
Use it for: Checking answers, simplifying fractions, divisibility questions in Olympiads and scholarship tests.
Worked example: How many factors does 72 have? → 12
Work it out in your head or on paper, then tap your answer — or type it and press Check. Stuck? Press “Show me how”.
Right: 0 · Tried: 0
🏁 Lesson 3 test
20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.
🏅 Sign in with Google to earn the
🔍 Divisor Detective badge when you pass — and a certificate when you finish all 10 lessons of
Part 1 · Number skills. You can still take the test without signing in.
👩🏫 Quantitative aptitude classes — live online, request a call back
Prefer a real teacher? TalentJR teachers take live online classes anywhere in India. Tell us what
you need and our team will call you with timings and fees.
💻Live online classesSmall groups or 1:1 with a teacher, from home, any city.
📞We call you backOur team asks what your child needs, then shares timings and fees.
🏠Home tutor?We are still building our list of home tutors — ask on the call if there is one near you.
