Help me and will give brainlessness

Rounding is simple:
For 82.98, we can round 82 to 83, since 82 is the whole number and the previous digit is 9 (so we round up).
For 169.645, we scratch off 45. Since 6 is in the tenth's place and the previous digit of it is 4, we leave it at 169.64.
:)