WEBVTT
00:00:00.960 --> 00:00:24.500
Use the symbol for is less than, is greater than, or is equal to to fill in the gap, 93423 take away 45111 what 59249 plus 23114.
00:00:26.240 --> 00:00:28.160
Here we have two expressions.
00:00:28.220 --> 00:00:31.730
One is a subtraction, and the other is an addition.
00:00:32.840 --> 00:00:34.700
And in between them, we have a gap.
00:00:35.560 --> 00:00:38.970
And we need to choose the correct symbol to use in between them.
00:00:39.610 --> 00:00:43.320
Is the first expression less than the second expression?
00:00:44.130 --> 00:00:46.720
Is it greater than the second expression?
00:00:47.340 --> 00:00:49.290
Or are the two expressions equal?
00:00:50.080 --> 00:00:54.250
Now, both expressions involve numbers that have five digits.
00:00:54.520 --> 00:00:59.710
So, we might think to ourselves that we need to calculate each answer before we can actually answer the question.
00:01:00.360 --> 00:01:03.880
But the question doesn’t actually ask us to calculate each value.
00:01:03.880 --> 00:01:05.720
We just need to complete the gap.
00:01:06.190 --> 00:01:12.560
And if we look carefully at the numbers we’re dealing with, we can actually answer the question without calculating anything.
00:01:13.070 --> 00:01:15.510
Let’s start by looking at our subtraction.
00:01:15.970 --> 00:01:24.060
Now, the first number in our subtraction, 93423, we could think of as being the same really as 90000.
00:01:25.270 --> 00:01:27.330
We’re just using this to give us an estimate.
00:01:27.980 --> 00:01:35.030
And we can think of our second number, which is 45111, as really being the same as 45000.
00:01:36.050 --> 00:01:43.350
Now, it’s quite helpful that this number is about the same as 45000 because 45000 is actually half of 90000.
00:01:44.290 --> 00:01:51.560
So, the answer to the subtraction is going to be approximately, and this is the symbol for approximately, 45000.
00:01:54.990 --> 00:01:58.930
Now, if we look across at the addition, you can see why we don’t actually have to work out anything.
00:01:59.520 --> 00:02:02.660
The addition begins with a number much greater than 45000.
00:02:02.960 --> 00:02:11.000
It’s 59249 and then we’re adding some more onto it, another 23114.
00:02:11.860 --> 00:02:16.110
We can see straightaway that this value is going to be greater than the first value.
00:02:16.590 --> 00:02:26.260
And so, without working out any of the values exactly, we can confidently say that the symbol we need to put in between both expressions is is less than.
00:02:26.560 --> 00:02:30.170
The first expression is less than the second expression.
00:02:31.160 --> 00:02:35.310
Now, although we don’t have to do this next step because we’re confident we’ve got the right answer.
00:02:36.090 --> 00:02:37.250
Let’s just prove it.
00:02:37.970 --> 00:02:39.630
Three take away one equals two.
00:02:40.390 --> 00:02:42.940
Two tens take away one 10 equals one 10.
00:02:43.410 --> 00:02:46.840
Four hundreds take away 100 leaves us with three hundreds.
00:02:47.400 --> 00:02:59.980
We can’t subtract five thousands from three thousands, so we can exchange one lot of 10000, which takes us now down to eight lots of 10000, and put it next to the three to give us 13 thousands.
00:03:00.830 --> 00:03:06.000
13 thousands take away five thousands equals eight thousands.
00:03:06.670 --> 00:03:11.650
And then eight tens of thousands take away four tens of thousands leaves us with four tens of thousands.
00:03:12.210 --> 00:03:15.980
The value of the first expression is 48312.
00:03:16.550 --> 00:03:21.430
So, we can see straightaway this is less than the number that we start the addition with in the second expression.
00:03:22.200 --> 00:03:24.040
Our estimation was correct.
00:03:24.940 --> 00:03:37.530
93423 take away 45111 is less than 59249 plus 23114.