The Add Up technique consists of introducing up from the selection remaining subtracted (subtrahend) to The complete (minuend). Begin by selecting challenges where the minuend and subtrahend are near jointly (e.g. 57 - 53 or 332 - 326) to construct an idea of subtraction as the distance concerning two numbers. https://www.generationgenius.com/videolessons/strategies-to-add-subtract-within-20-make-a-10-doubles-facts/