Here is a part-whole model. Sometimes the model is rotated. It looks different, but it still has two parts and a whole. We can use this model to help us solve problems. We can put 4 things in one of ...

Learn about number bonds to 100 using tens and ones. Add 2-digit numbers Learn how to add two-digit numbers. Adding 3-digit and 1-digit numbers together Explore examples and a video to show how to add ...

In early 15th century Europe, the letters P and M were generally used for addition and subtraction. Why is the plus sign used for addition and the minus sign for subtraction? In early 15th century ...

Korean children's ability to solve addition problems with sums of 10, single-digit addition problems with sums between 10 and 18, and single-digit subtraction problems with minuends between 10 and 18 ...

Karen C. Fuson, Diana Wearne, James C. Hiebert, Hanlie G. Murray, Pieter G. Human, Alwyn I. Olivier, Thomas P. Carpenter and Elizabeth Fennema Researchers from 4 projects with a problem-solving ...