My daughter has this problem:
Laura found 67 x 436 by multiplying and subtracting. Show how Laura found the product. I showed my daughter the multiplication method and then used division for the subtraction. Was this right?
My daughter has this problem:
Laura found 67 x 436 by multiplying and subtracting. Show how Laura found the product. I showed my daughter the multiplication method and then used division for the subtraction. Was this right?
Hi Barb,
The typical way to evaluate 67 x 436 is by multiplying and adding: (60 + 7) x 436. Usually this is written as:
436
x 67
---------
3052 = 436 x 7
+ 26160 = 436 x 60
----------
29212
Alternatively, you could evaluate 67 x 436 by multiplying and subtracting: (70 - 3) x 436.
436
x 67
---------
30520 = 436 x 7
- 1308 = 436 x 3
---------
29212
Although you get to the same answer both ways, one or the other method may be easier. For example, consider 48 x 713 = (40 + 8) x 713 = (50 - 2) x 713. In this case, multiplying and subtracting is easier (for me!) because it involves multiples of 5's and 2's rather than of 4's and 8's.
Hi, Barb.
I do not know the particular method this assignment is looking for, but here is one way to get the product using mutiplication and subtraction:
Round 67 to 70.
Multiply 436 x 70, which is an easier multiplication problem.
Since 70 is 3 more than 67, this product has 3 extra "436"s. From the product, subtract 436 three times.
436 x 70 = 30,520
30,520 -436 = 30,084
30,084 -436 = 29,648
29,648 -436 = 29,212
67 x 436
= 436 x (70-3) <== since 67 = 70 - 3
= 436 x 70 - 436 x 3 <==Multiplication and subtraction
= 30520 - 1308
= 29212
Comments
thank all of you soooo much! this should make things easier for me when we have to study for a math test!! i was just completely stumped by this fourth grade problem! need to boost my math skills I guess. I still have 8 more years of problems getting difficult for her, not to mention 2 younger brothers that will be going through the same thing, lol! THANKS AGAIN!!!!