Math · Stage 2
Tens-first hops & adjust
Add and take away 2-digit numbers in your head — jump the tens first, then adjust.
✦ Math📘 Stage 2 · S2⏱ ~9 min🧒 Ages 6–7★ Free to start
I can add and subtract 2-digit numbers in my head using tens-first hops and rounding-and-adjusting.
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Kavi's Leapfrog Pond 🐸
Kavi is leapfrogging across the pond! "To do 47 + 30 in my head, I take three big ten-hops — 57, 67, 77!" Then a tricky one: 47 + 29. "Nearly thirty… so I'll hop a whole 30 to 77, then step back 1 — 76!" That clever step-back is called adjusting.
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What your child will learn
1Jump the tens firstTo add a 2-digit number in your head, jump the tens before the ones. Each giant hop is +10 — a whole ten. Tap Hop +10 and watch Kavi leap 0 → 10 → 20 → 30 → 40.
2Round up, then adjustWhen you add a number that is nearly a ten — like 9, 19 or 29 — hop the easy round ten first, then step back. Tap Hop +10 to see the big friendly jumps.
3Bonds that bridge the tenWhen your ones hop crosses a ten, lean on your bonds to 10. Know these cold and 48 + 6 is instant: 48 + 2 makes 50, then 4 more → 54.
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A peek inside
Kavi has 47 acorns 🌰 and gathers 30 more. How many now?
tens-first: 47 → 57 → 67 → 77
Try this at home: Tens first: 47 + 30 = __ · 53 + 20 = __
Part of Math · Stage 2 · S2 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.