Estimating and Calculating Sums
1. Make the best estimate you can for the following addition sums. Choose whichever method of estimating you prefer. a) 2487 + 1729 + 4234 + 7520
c) 28 + 142 + 1969 + 12856 e) 745 + 2690 + 1261
b) 913 + 1105 + 6349 d) 16908 + 7089
f) 478 + 512 + 520 + 491
g) Now use your calculator to calculate the total of each sum. Compare the answer to your estimate.
2. Use your calculator to work out the answers to these.
a) 4985 7083
+ 2680
g) 33572 25297
+ 38474
b) 9158 12775
+ 8056
h) 20759 21604
+ 33031
c) 11,907 15048
+ 3763
i) 37883 41478
+ 26339
d) 19138 18560
+ 21524
j) 43056 37712
+ 23563
3. In a recent vote to decide whether cats should be banned from driving cars, 13597 said that they should be banned, 9711 said that they shouldn’t and 3819 said that they had no opinion. How many people voted in total?
4. On a trip to Australia, Tom fl ew 4759km to Mumbai, where the plane refuelled, and then fl ew a further 3465km to Sydney. What was the total length of the plane journey?
Puzzler
Estimate the number of children in the school whose fi rst name begins with C.
Use the names of the people in your own class as a way of making a good guess. Survey all the classes in the school to see what the exact number is. Did anyone get it right?
28 Operations 1
e) 8309 28739
+ 14833
k) 37225 47038
+ 43886
f) 23966 31059
+ 28644
l) 51578 29663
+ 46716
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