Multiply faster
Multiply anything by 9, 99, 999 instantly
Strings of 9s create long carry chains in standard multiplication — but they are just one less than a power of 10.
Spot it when
The multiplier is all 9s: 9, 99, 999, 9999.
Watch it solved
Identify the multiplier type
99 is a string of 2 nines, so use the "one less than before" shortcut.
⚡ Speed Advantage
9× faster with Vedic Mathematics
When you’ll actually hit this
Real moments — exams, homework, competitions — where this shortcut earns its keep.
Quick till maths: seven items at ₹99 each, total before the customer asks.
One less than 7 is 6; complement of 7 is 93 → 693.
A speed-arithmetic round throws up 423 × 999 — the kind that looks designed to eat time.
Left 423−1 = 422, right complement 1000−423 = 577 → 422577, in one step.
A bulk order of 43 units at ₹99 apiece, totalled mentally.
Left 42, complement 57 → 4257.
The method behind it
एकन्यूनेन पूर्वेण
Ekanyūnena Pūrveṇa
“By one less than the previous one”
Multiply by a string of 9s: subtract 1 from the multiplicand for the left part; find the complement of the multiplicand for the right part.
via long multiplication — 9 partial products.
left=422, right= (1 step).
Use when
- • Multiplying by 9, 99, 999, 9999, etc.
Avoid when
- • Other multipliers