Geniuses! How to solve x²=10.5*10^-14 without a calculator

Thank you so much in advance :)

its √10.5 * 10-7

Have fun calculating √10.5 by hand. We know it's a number slightly greater than 3 because √9 = 3 and √16 = 4.

x² = 10.5*10^-14
x = √(10.5)*10^-7