AA
Use the number line to model jumping up a tidy number...
Play around and learn with these fun blocks. Add and count ten hundreds then convert them into thousands.
Jump up in tens and stop BEFORE you reach the target number. Then add the ones.
Use the number line to record your thinking.
Learn to compensate with this fun little activity.
Learn to solve problems like: 78 + 99.
METHOD ONE
- Make 78 with tens and ones.
- Add on 100.
- But this is one too many!
- Take one away.
METHOD TWO
- Transfer one from 78 to the 99.
- 77 + 100 = 177
Use the handy number line applet to model the problem.
'For a problem like 445 - 398, the fact that 398 is very close to a tidy number, namely, 400, suggests that a useful way of solving it is by equal additions, in this case, of 2.'
- 445 - 398 = 47
- 447 - 400 = 47 (Easier!)
Adjust the scale to the right and click 'check' to see if the equations are equal.
Learn to bust those easy combos first! Make 10.
9,999... Watch the roll over.
Adding large numbers in your head can be a real challenge. Take it easy by using the following methods:
Practise adding larger numbers.
A useful teacher tool to demonstrate regrouping of units and tens as well as standard form addition.
Subtracting large numbers can be difficult. Try the following methods:
- 2 digit subtraction (no regrouping)
- 2 digit subtraction (regrouping)
- 3 digit subtraction (regrouping)
Improve your estimation skills. The faster and more accurate your answer the bigger the score.
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