Square any two-digit number
From the sutra Ūrdhva Tiryagbhyām, Vertically and crosswise, used for squares
, in Bharati Krishna Tirtha's 1965 book Vedic Mathematics. Deep dive into the sutra
Try it with your numbers
When to use it
Squaring any two-digit number, like 47² or 83².
The idea
For ab²: write a², then 2 × a × b in the middle, then b², and carry from right to left.
Worked example: 47²
- 16 | 56 | 49Digits 4 and 7. Left: 4² = 16. Middle: 2 × 4 × 7 = 56. Right: 7² = 49.
- 16 | 56 | 49Keep one digit in each of the middle and right spots and carry the rest leftwards.
- 2209So 47² = 2209.
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.