Computation Race 2

Let's have a race between brains and calculators. If you are using a calculator, you must find answers to all the problems with a calculator. If you're using your brain, you are welcome to use paper.

1.
10
+56
 2.
100
+56
 3.
1,000
+56
4.
10,000
+56
 5.
100,000
+56
 6.
7
+2
7.
70
+20
 8.
700
+200
 9.
7
–2
10.
70
–20
 11.
700
–200
 12.
9
+4
13.
90
+40
 14.
900
+400
 15.
9,000
+4,000