Registers are useful tools when writing KeyboardMacros. Notice how you can store numbers in registers, insert them again, and increment them in the register.
See the Node Keeping Numbers in Registers in the EmacsManual.
‘C-u 1000 C-x r n x’
‘C-x r i x’
C-x r + x’
‘C-u 50 C-x e’ to run the macro 50 times.