To write a number in scientific notation, you need to write the number as the product of a number from 1 to under 10 and an integer power of 10.
Start by moving the decimal point until you have a number from 1 to under 10.
By moving the decimal point 2 places to the right, you end up with 7.65 which is from 1 to under 10. Having moved the decimal point 2 places to the right, you multiplied the number by 100. Now you need to divide 7.65 by 100 to get back to the original number.
0.0765 = 7.65/100 = 7.65 * 1/100 = 7.65 * 1/10^2 = 7.65 * 10^-2
0.0765 = 7.65 * 10^-2