two towers, one taller than the other

Subtraction

14 lessons

  1. AYour Subtraction Starting Pointfind a comfortable place to begin taking away
  2. 1Zap Them Awaytake dots away, one zap at a time
  3. 2Two Stacks, One Differencecompare two stacks to find the gapComet CatcherPlay
  4. 3Jump by Onescount the jumps along the line
  5. 4One Big Leapone leap instead of many jumps
  6. 5Leaps Past a Thousandthe same leap, with bigger numbers
  7. 6Big Jumps: Tensjump ten at a time
  8. 7Big Jumps: Hundredsjump a hundred at a time
  9. 8Big Jumps: Thousandsjump a thousand at a time
  10. 9Take Away in Columnstwo-digit subtraction, place by place
  11. 10Ten Comes Backopen a ten when the ones run short
  12. 11Borrow and Take Awaycolumn subtraction with borrowing
  13. 12The Gap Stays the Samechange both numbers, keep the difference
  14. 13Adding Below Zerosubtracting is adding a negative