The challenge for 1st class

That is such a problem classmate asked her sister in the first grade. We solve?





if you can not see:
6399-3
1043-1
5444-0
6301-2
8036-4
0631-2
8048-?
zy.ya know the answer ... poprubuyte answer and explain the answer and not ugodat it.If those not in the evening I otpishu right decision

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