Optellen tot 1000 (HTE + T = HTE) - oefening 1

Optellen tot 1000... hoe doe je dat?
163 + 70 = ( 163 + ) + =
152 + 90 = ( 152 + ) + =
354 + 60 = ( 354 + ) + =
483 + 80 = ( 483 + ) + =
529 + 90 = ( 529 + ) + =