13: SQUARING NUMBERS, ENDING IN 5

SUTRA (Algorithm):

Read & Work FROM LEFT

Leave the last digit, 5;
Remaining digits make-up the 'REST'
'REST' x NEXT HIGHER NUMBER | 25

Demonstration (1): 352 = ?

sq 5 ending

In 35, take away the '5', the REST is '3'.

352 = 3x4 | 25 = 12 25

Demonstration (2): 452 = ?

452 = 4x5 | 25 = 2025

Demonstrations:

  1. 852 = 8x9 | 25 = 7225
  2. 1052 = 10x11 | 25 = 11025
  3. 1552 = 15x16 | 25 = 24025
  4. 2552 = 650 | 25 = 65025
  5. 3152 = 992 | 25 = 99225
  6. 3252 = 1056 | 25 = 105625
  7. 7052 = 4970 | 25 = 497025
  8. 20052 = 40200 | 25 = 4020025
  9. 21052 = 44310 | 25 = 4431025

Just write the squares on the right, mentally:

  1. 152 =
  2. 252 =
  3. 1152 =
  4. 1252 =
  5. 1352 =
  6. 1452 =
  7. 1552 =
  8. 1652 =
  9. 2152 =
  10. 3252 =
  11. 6152 =
  12. 7552 =
  13. 11052 =
  14. 21052 =
  15. 10552 =