Yes it is 21 if you're adding. (17 + 4 does equal 21):
kind of because a one has to go on top of the first *1" in 17 which helps you get the result of 21
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1
17
+. 4
-------
21
So, firstly we do 7 + 4 which gives you 1, right?
Secondly, we do 1 + 1 which gives you 2, right ? because we had a one on top of the 1 on top of the on in 17
Sorry, if I repeated a step... I'm trying to make you understand the problem / question better
