Subtract from 100, 1000, 10000

From the sutra Nikhilaṃ Navataścaramaṃ Daśataḥ, All from 9 and the last from 10, in Bharati Krishna Tirtha's 1965 book Vedic Mathematics. Deep dive into the sutra

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Number to subtract

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When to use it

Subtracting from a power of ten, like 1000 − 387 or 10000 − 2456 (change at the store).

The idea

Subtract every digit from 9, except the last one, which you subtract from 10. No borrowing at all.

Worked example: 1000 − 387

1. 3 8 71,000 − 387: write the digits of 387.
2. 6 1 3Each digit from 9: 9−3=6, 9−8=1. The last from 10: 10−7=3.
3. 613So 1,000 − 387 = 613.

Practice this trick

All 15 speed tricks, each with its calculator. The speed tricks use sutras from Bharati Krishna Tirtha's 1965 book Vedic Mathematics; the lessons, problems and pictures here are our own.