Multiply by 5

What This Drill Trains

Multiplying by 5 has a reliable shortcut that feels like a magic trick until it becomes ordinary: half of ×10, or “double then add a zero” depending on how you phrase it. Because ×5 shows up in time (minutes), money, and averages, this dedicated drill pays off quickly outside the game.

How to Think During the Round

Two equivalent shortcuts: (1) multiply by 10, then take half; (2) if the number is even, take half and append a zero. Example: 18 × 5 → 180 ÷ 2 = 90, or half of 18 is 9 → 90. For odd numbers, use ×10 then half: 17 × 5 → 170 ÷ 2 = 85.

You have 60 seconds. Accuracy still outranks raw speed: one calm method repeated well beats a streak of guesses. After the timer ends, notice which problems felt sticky — that short review is where real improvement happens.

Worked Examples

Study these before you press Start. Try to recreate the thinking without looking at the answer first.

Common Mistakes

• Appending a zero without halving first (turning 18×5 into 180).
• Halving incorrectly when the number is odd and skipping the ×10 route.
• Confusing the ×5 shortcut with the ×11 split-and-add pattern.

Practice Tips

• Pick one shortcut and stick with it for the whole round.
• Even numbers should feel almost instant; spend warm-up time on odds.
• Check an answer occasionally by thinking “five groups of n” for reasonableness.

Suggested Session Plan

1. Read the method section once if this skill is new.
2. Cover the answers and re-solve the three worked examples aloud.
3. Start the timed round and stick to one strategy.
4. Replay once, then write down any fact or pattern you missed.
5. If the same error repeats, open the full lesson for more examples and a practice set with an answer key.

Full explanation, extra worked examples, and practice problems for this skill: open the related stage lesson .

Prefer a structured curriculum instead of random drills? Browse all learning stages or read the complete mental arithmetic guide . More timed drills live on the games hub.