If you look at a problem and estimate the solution before doing any calculation, you will help yourself a ton! It will help you avoid the mistake of putting your decimal point in the wrong place.
Sometimes you HAVE to estimate, because a problem tells you to do so. This video will help you GET this idea and use it effectively, and FAST!
Summary of this video:
START 0:20. intro
0:21 0:40 Estimate, then calculate. 0:25 x 62. Round 62
0:41 1:03 Think about 0.25 and what it means for the question. Visual demo of thinking to estimate
1:04 1:55 Calculate. Significant figures. Standard algorithm used. Decimal point in right place. Compare to estimated answer.
1:58 2:29 Estimate first, then calculate to avoid mistakes.
2:30 2:40 Second example: 11.59 x 2.84. Estimate first, using rounding.
2:41 2:48 Primer for what to expect in answer
2:49 3:05 Solve with calculator. ERROR in answer.
3:06 3:18 Find and fix the error.
3: 19 3:31 Imagine if I had not done the estimate...
3:32 3:52 replay with slow motion of what went wrong with the calculator. I want students to be aware if it goes in wrong, it comes out wrong, so take care!
3:52 4:03 Use estimation, gain confidence, get more work right.
4:07 4:35 Third example: 0.8 x 1.983
You might be told simply to estimate your answer... Do NOT calculate with the given numbers, you WILL lose marks.
4:36 5:00 Round the numbers, done with place value chart.
5:01 5:12 Multiply rounded figures. Easypeasy!
5:15 5:27 Rounding is a key concept
5:27 5:45 Next time: Shortcuts to multiplying decimals, including clickable link.