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Bridge to 10

📘What it is

The "through 10" technique! First reach 10, then add the rest. A clever method!

🛠️How it works

8+7 = 8+2+5 = 10+5 = 15. Reach 10 first!

🔢A worked example

Take 8 + 5: first complete 8 to 10 (8 + 2 = 10), then take the used 2 from 5 and add the remaining 3 to 10 → 13. In other words, you build a bridge over 10 first.

🎓A closer look

The Bridge of 10 splits the number being added into two easy steps: first top up the larger addend to 10, then add what is left. For 7+6, seven needs 3 to reach ten, so 6 is split into 3+3 — 7+3=10, then 10+3=13. In subtraction the bridge is built downwards: for 15−7 you first take away 5 to land on 10, then remove the remaining 2 to get 8.

The method needs no abacus — it is pure mental arithmetic, which is why it matches the school curriculum directly. It also underpins mental multi-digit addition: in 38+7 a child tops 38 up to 40 and adds the remaining 5. The key skill formed here is flexibly breaking a number apart to fit the task.

  • Age: 6-8 (grades 1-2); the pairs of 10 must be known confidently first.
  • Common mistake: splitting the larger number instead of the smaller addend.
  • Practice tip: say the steps out loud at first: "add three — ten, three more — thirteen".

💡Why it helps

This teaches your brain to take "two small steps" — making complex problems simple.

❓Frequently asked questions

Bridge of 10 is a way of first making 10 and then adding the remainder, that is the carrying technique for crossing into a new ten. It makes additions that go past 9 easier for a child.
It helps when a sum goes beyond 10 and crosses into the next ten: the child first completes up to 10, then adds the remaining ones on top.
This technique relies on knowing the friends of 10, so it is best learned after the child has mastered the pairs and the idea of a ten.
Yes, on MentalMath you can learn the Bridge of 10 technique and do the exercises for free and without registration.

Other methods

🧮 Abacus (Soroban) — the foundation of mental arithmetic 🔟 Friend of 10 🤝 Big Friends 👬 Big Brother ✨ ×11 Magic 9️⃣ ×9 Technique 🕛 ×12 Technique 🕉️ Vedic Math (100) 🔱 Vedic Math (1000) ✖️ Urdhva-Tiryagbhyam — vertical and crosswise multiplication 🔲 Squaring a number — the fast way ➗ Division
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