Multiply any two numbers in one line

From the sutra Ūrdhva Tiryagbhyām, Vertically and crosswise, in Bharati Krishna Tirtha's 1965 book Vedic Mathematics. Deep dive into the sutra

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First number Second number

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When to use it

Any multiplication. Fastest for 2-digit and 3-digit numbers.

The idea

Work right to left one column at a time. Multiply straight down, then crosswise, then straight down again, carrying as you go.

Worked example: 21 × 13

1. 3Column 1 (straight down): 1×3 = 3. Write 3.
2. 73Column 2 (crosswise): 1×1 + 2×3 = 7. Write 7.
3. 273Column 3 (straight down): 2×1 = 2. Write 2.
4. 273So 21 × 13 = 273.

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.