Add four-digit numbers, using disks in a place value chart. Problems involve both no regrouping and regrouping in one place
B. Add two 4-digit numbers with and without regrouping in two places using column addition and a disk model
C. Add two 4-digit numbers with and without regrouping in one place using a disk model part II
D. Add multi-digit numbers with regrouping in multiple places using column addition and disk models
E. Add multi-digit numbers with regrouping in multiple places using column addition
F. Add multi-digit numbers using the standard algorithm