Question

estimate the difference of the decimals in 77.330 -4.602 =
77.3=80 ,4.6=5

Answer 1

77.330 = 77
4.6 = 5
77 + 5 = 82

Answer 2

blanca,
after the decimal, if the number is 5 and above you plus one to the number in front of the decimal.
if the number after the decimal is 4 and below then treat it as zero.