Add and subtract within 20

What you’ll practice

Adding and subtracting within 20 is a key step toward stronger mental math and smoother work with bigger numbers later. This quiz mixes simple facts with slightly trickier ones so you can improve without getting stuck.

Each question has 4 answer options and there’s no timer, so players can think carefully, use strategies, and learn from mistakes.

Difficulty and question settings

You can choose your question count before you start, and you can also select a difficulty level (easy, medium, hard, or mixed). Mixed mode balances the challenge by blending straightforward facts (like 6+3) with problems that require a strategy (like 13−8).

Common pitfalls to avoid

Many errors come from rushing, mixing up + and − signs, or losing track when counting back. Slow down, check the operation, and use a consistent method.

• Watch the sign: addition and subtraction look similar when you’re moving fast
• Use “make 10” (8+7 = 8+2+5) to reduce counting
• For subtraction, count up from the smaller number to the bigger number when it feels easier
• Double-check teen numbers (11–19) to avoid digit swaps
• If you guess, pause and estimate whether the answer makes sense

Tips to improve quickly

Try a short set each day, then increase the question count as you get more accurate. When you miss a problem, redo it using a different strategy (number line, counting on/back, or making ten) to lock it in.