WEBVTT
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Complete the sequence: 5939, 5932, 5925, what, what, what, and what?
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All the whats as we read the question show that there are four missing numbers to this sequence.
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And the question is asking us to find them to complete the sequence.
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To do this, we need to look at the three numbers that we’ve been given already and try and work out what the rule for the sequence is.
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Our numbers are 5939, 5932, and 5925.
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What do we notice about these numbers?
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Well, the first thing we can say about the sequence is that it’s a decreasing pattern.
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As we go from one number to the other, the numbers are getting less and less.
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But by how much?
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Our first number has five thousands, nine hundreds, three tens, and nine ones.
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Our second number has five thousands, nine hundreds, three tens, and two ones.
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The number of thousands has stayed the same, as has the number of hundreds and also the number of tens.
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In fact, the only part of the number that’s changed is the ones.
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We’ve gone from nine ones to two ones.
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How do we get from nine to two?
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Well, we know that two and seven make nine.
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So nine take away seven will leave us with two.
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Let’s see whether subtracting seven is the rule for the pattern.
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We’ll have a look at the next number.
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We have five thousands, nine hundreds.
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This time, the tens digit has changed and the ones digit.
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If we look at the number we were starting from, it ended in 32.
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And 32 take away seven does equal 25.
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The next number in the sequence will be 5925.
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Now that we know what the rule for the sequence is, we can find our remaining four numbers.
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We know that 25 take away seven equals 18.
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And so 5925 take away seven will be 5918.
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5918 has eight ones.
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So we can subtract seven quickly.
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Eight take away seven equals one.
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So the next number in our sequence is 5911.
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Seven plus four equals 11.
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So if we take away seven from 5911, we’re left with 5904.
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Finally, we can split the seven that we want to subtract into four and three.
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If we take away four from 5904, we’re left with 5900.
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Now if we take away the remaining three, we’re left with 5897.
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We’ve found that our sequence was a decreasing one and that the rule was to take away seven each time.
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The completed sequence is 5939, 5932, 5925, and then our four missing numbers, 5918, 5911, 5904, and 5897.