One-Digit Addition
Introduction
Practice adding any two single-digit numbers (0–9) until it becomes automatic. These 100 basic facts form the foundation of all future arithmetic.
Single-Digit Facts (The Addition Table)
There are 100 basic addition facts, from 0+0=0 to 9+9=18. Memorizing these facts is as important for mathematics as knowing the alphabet is for reading. Once these facts are automatic, all higher arithmetic becomes much faster and easier.
Key patterns to notice: • Adding 0 never changes a number (identity) • Adding 1 gives the next counting number (successor) • Doubles: 1+1=2, 2+2=4, 3+3=6, 4+4=8, 5+5=10… • Near-doubles: 3+4=7 (one more than 3+3=6)
Quick practice
Using a sample question until this lesson includes practice data. XP sync rolls out with account progress (Phase 4).
Quick warm-up: what is 4 + 3?
For the full tabbed flow with scoring summary, open the Practice tab above.