AC Lim's answer to shu's Primary 3 Maths Singapore question.
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Hope this helps
Date Posted:
3 years ago
First number has 1 digit.
Second number has 2 digits.
Third number has 3 digits.
Last number has 50 digits. So the last number is the 50th number.
Since there are 50 numbers and they are all made up of '1's, there are 50 '1's in the ones' place.
50 x 1 = 50
Their total is 50. This equals 5 tens. So it's adding a '5' to the tens' place. And the ones' place is now a '0'
Now all the numbers have a '1' in the tens place except the first number. So that's a total of 49 '1's in the tens' place.
49 x 1 = 49. That's 49 tens.
Add the 5 from before,
49 + 5 = 54
There are 54 tens in total. That's equal to 5 hundreds and 4 tens. So a '5' is added to the hundreds' place, leaving a '4' in the tens' place.
So the last 2 digits are 4(tens' place) and 0(ones' place)
Second number has 2 digits.
Third number has 3 digits.
Last number has 50 digits. So the last number is the 50th number.
Since there are 50 numbers and they are all made up of '1's, there are 50 '1's in the ones' place.
50 x 1 = 50
Their total is 50. This equals 5 tens. So it's adding a '5' to the tens' place. And the ones' place is now a '0'
Now all the numbers have a '1' in the tens place except the first number. So that's a total of 49 '1's in the tens' place.
49 x 1 = 49. That's 49 tens.
Add the 5 from before,
49 + 5 = 54
There are 54 tens in total. That's equal to 5 hundreds and 4 tens. So a '5' is added to the hundreds' place, leaving a '4' in the tens' place.
So the last 2 digits are 4(tens' place) and 0(ones' place)
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