Subtraction base 5 - Math Central

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Question from nakita, a student:

can u explain the quinary subtraction...
(3000) -(2342) all the numbers are in quinary number system

Hi Nakita

I would think of this as an addition problem rather than a subtraction problem

What would you add to 2342₅ to get 3000₅?

Displaying it as we often do with an addition problem. Find the values of the questions marks if this addition is true in base 5.

	2	3	4	2
	?	?	?	?
+	_____	_____	_____	____
	3	0	0	0

I can help you with the units digit. Since two plus three is five and five in base five is 10₅, the units digit of the difference between 3000₅ and 2342₅ is 3 and hence

	2	3	4	2
	?	?	?	3
+	_____	_____	_____	____
	3	0	0	0

If you learned the addition algorithm the way I did then you carry a 1 into the fives column. What is the value of the question mark in the fives column? What is the value of the question mark in the five squared column? What is the value of the question mark in the five cubed column?

You can use addition base five to check if your answer is correct.
Penny

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