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The digital root of a number is what you get by adding its digits until one digit is left. It lets you check a multiplication answer without doing the sum again.
✓ You passed this trick’s test.
Gunita Samuccayah — “the product of the sums is the sum of the product”
Use it for: Checking multiplication, addition and squares in exams. (It cannot catch every mistake — swapped digits keep the same root.)
Check: 23 × 41 = 943 → 9 + 4 + 3 = 16 → 1 + 6 = 7 ✓
Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.
Right: 0 · Tried: 0
20 sums. Check each answer, then go to the next one. Get 16 or more right to pass.
🏅 Sign in with Google to earn the 🕵️ Answer Detective badge when you pass — and a certificate when you finish all 10 tricks of Part 2 · Advanced tricks. You can still take the test without signing in.
Why does it work? When should you use it? Ask in English, मराठी or हिंदी.
Sign in with Google to ask Free — 20 questions a day.
Prefer a real teacher? TalentJR teachers take live online classes anywhere in India and visit homes in selected cities. Tell us what you need and our team will call you with timings and fees.