Optellen tot 1000 (HTE + T = HTE) - oefening 3

Optellen tot 1000... hoe doe je dat?
665 + 60 = ( 665 + ) + =
285 + 70 = ( 285 + ) + =
888 + 30 = ( 888 + ) + =
672 + 50 = ( 672 + ) + =
429 + 90 =( 429 + ) + =