... a standard algorithm and carry out the procedures mechanically – without thinking about number meaning in the algorithm. As such, they have little understanding of whether the results in their ... the first addend to the tens of the second addend (36 + 40 = 76), and then add on the ones of the second addend (76+7=83);• add the first addend to the ones of the second addend (36+7 =43 ), and ... operations in different ways. There are four main types of addition and subtraction problems:joining, separating, comparing, and part-part-whole. A joining problem involves increasing an amount...