Robert Malmodo

Just calculated 27 x 3 on my fingers. It takes 2 seconds and doesn't use a calculator.

[Robert Malmodo @100fingerz]

53 squared? 2,809. 57 squared? 3,249. See the pattern? #mentalmath #mathemagic

[Robert Malmodo @100fingerz]

Square any 2dig# ending in 5: Mult 1st dig by next higher dig and put 25 after. 35 sqrd (3x4 put 25 = 1,225). 55 sqrd=3,025. #mentalmath

[Robert Malmodo @100fingerz]

Quick. In 2 seconds or less add 23, 17, 19, and 9 with your fingerz. It's easy #chisanbop #fingermath #soroban