Answer:
when adding you just line the decimals up like this, let's say you had to add 1 to 2.58.
2.58
+ 1 .00
3.58
when multiplying you might have to move it, say you had to multiply 1.5 by 2.2. (you don't have to line up the decimals like with addition)
1 .5
× 2.2
30
+ 300
3.30
1.5 has one decimal place and 2.2 also has one decimal place so you put those 2 decimal places in your answer.
sorry if this is a bit confusing lol
