Every pair that makes 5, 10 or 20 — as a chart to learn from, a drill to check with, and printable sheets for the fridge door. Abacus students know these as the small and big friends.
No signup. The chart, the drill and the printables all run right here in your browser.
Bonds to
The pairs
Read them, say them, cover one side and recall the other. Fluency with these pairs is what makes carrying and borrowing feel obvious later.
What Western classrooms call number bonds, abacus training calls the small friends (pairs making 5) and big friends (pairs making 10) — and drills them until every carry is a single bead move. If your child is learning bonds at school, the abacus route makes them permanent.
A number bond is a pair that adds to a fixed total — 6 and 4 bond to 10. The chart above lists every pair for the base you pick — 5, 10 or 20 — including the 0 pair, because knowing that 0 and 10 belong on the list is part of the idea. Each bond is also a subtraction fact: 6 and 4 make 10, so 10 minus 6 is 4.
How are number bonds different from small friends and big friends?+
The facts overlap; the use does not. Small friends are bonds to 5 and big friends are bonds to 10, but on a soroban they are bead instructions: the rod has run out, so add 5 and take the small friend off. A number bond is just the fact. Bonds to 20 have no bead rule at all — they are school arithmetic, not abacus technique.
Which base should a child start with?+
Start at 5, then 10, then 20 — the picker switches base and re-deals the drill. Bonds to 5 are what Elementary A needs for small friends and bonds to 10 are what Elementary B needs for big friends, so the first two bases pay off directly in bead work. Bonds to 20 are extra school arithmetic with no bead rule behind them.
Is there a printable number bonds worksheet?+
Two, from the buttons under the drill. Print chart puts every pair for the chosen base on one page; print sheet gives twenty blanks in the form blank plus a number equals the total. The sheet is fixed per base, so reprinting hands out the identical paper to a whole class. Both print straight from the browser — no signup, no download, no watermark.
Does the drill mark the answers?+
Yes. Type the missing number in each of the ten questions and Check marks every row and reports a score; New round deals a fresh set from the same base. Editing an answer after a check clears the verdict rather than leaving a stale one. Judge fluency by pauses, not by the score — a bond counted out on fingers is not yet known.