10% of what equals 5?

2 Answers
Nov 15, 2017

Answer:

See a solution process below:

Explanation:

"Percent" or "%" means "out of 100" or "per 100", Therefore 10% can be written as #10/100#.

When dealing with percents the word "of" means "times" or "to multiply".

Finally, lets call the "(blank)": "n".

Putting this altogether we can write this equation and solve for #n# while keeping the equation balanced:

#10/100 xx n = 5#

#1/10 xx n = 5#

#color(red)(10) xx 1/10 xx n = color(red)(10) xx 5#

#color(red)(10)/10 xx n = 50#

#1 xx n = 50#

#n = 50#

10% of #color(red)(50)# = 5

Nov 15, 2017

Answer:

10% of 50 = 5

Explanation:

To find 10% of any number, move the decimal point to make it one place smaller.

Ex:
10% of 100 = 10
10% of 250 = 25
10% of 60 = 6

10% of 121 = 12.1
10% of 250.5 - 25.05
10% of 60.003 = 6.0003

10% of 0.44 = 0.044
10% of 0.003 = 0.0003
.......................

10% of a number equals the amount you would have to take ten times in a row to bring back the original number.
Ex:

#10%# of #42 = 4.2#
... and #4.2 xx 10 = 42#

#10%# of #50 = 5# because #5 xx 10 = 50#
...................................

Clearly you can just find 10% of 50 by multiplying:
#0.10 xx 50 = 5#

But I don't like to encourage students to solve "10 percent" problems that way because the answers should be spontaneous.

Here's the real reason that the answer is "50" to the question
"10% of _ = 5"
It's because 10% of 50 = 5
is something you know automatically.

You will automatically know all 3 ways to complete that math sentence when you automatically know
10% of 50 = 5

1) 10% of 50 equals how much?
10% #xx# 50 = ??
Answer: 10% of 50 = 5

2) 10% of what number equals 5?
10% #xx# ?? = 5
Answer: 10% of 50 = 5

3) What percent of 50 is 5?
?? % #xx# 50 = 5?
Answer: 10% of 50 = 5

These questions are all just three different "fill in the blank" questions to complete the automatic fact that
0.10 #xx# 50 = 5
10% of 50 = 5