Q:

# patterns on the multiplication table

I am having problems with a question my son gave me from school.
Use the rule 1 less than 3 times the number to make a pattern. Start with 5. What is the 4th number in the pattern?
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> 60 days ago

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writes:
Hi there,

The rule "1 less than 3 times the number" makes this equation: 3x-1

1st number: 3(5) - 1 = 14
2nd number: 3(14) - 1 = 41
3rd number: 3(41) - 1 = 122
4th number: 3(122) - 1 = 365

Hope that helps
> 60 days ago

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Hi Peterpoter71,

The rule is “1 less than 3 times the number”, l less means subtraction, 3 times means multiplication, you’re looking for the “number” so it’s unknown and thus you are write it as the variable X.  This all translates to the equation:

3x -1

Starting with the number  5 and plugging it into the above question will yields:

First number: 3 (5) – 1 =14
Second number: 3 (6) -1 = 17
Third number: 3 (7) – 1 = 20
Fourth number: 3 (8) – 1 = 23
Fifth number: 3 (9) – 1 = 26

The fourth number is 23.  As you can see, from your answers it’s 14, 17, 20, 23, 27.  Thus, your pattern is  plus 3 (+3)  or increasing by three as you go to the next number.

Hope this helps!

Vicki
> 60 days ago

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This is a typical example of an extremely poorly worded maths question. For starters, it is ambiguous, because it doesn't state whether to use the result of one step to get the result of the next. So, there are 2 sets of answers.

What the question might actually be asking is this:

"Start with the number 5. Apply the rule 1 less than 3 times that number to get a new number. Apply the same rule to that number to get a new number, and so on. What is the 4th number in this progression?"
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