count the leading zeroes, and add 1:
2.4*10^-4
look:
2.4 = 2.4*10^0
.24 = 2.4*10^-1
.024 = 2.4*10^-2
.0024 = 2.4*10^-3
.00024 = 2.4*10^-4
convert to scientific notation....0.00024
3 answers
2.2.4x10
69^69