Move the decimal 1 times to right in the number so that the resulting number, m = 6.15, is greater than or equal to 1 but less than 10
Since we moved the decimal to the right the exponent n is negative
n = -1
Write in the scientific notation form, m × 10n
= 6.15 × 10-1
Therefore, the decimal number 0.615 written in scientific notation is 6.15 × 10-1 and it has 3 significant figures.