The length of a straw is 19.7 cm when rounded to the nearest tenth cm. Which of the following is the largest possible length of the straw?

Question

Quizplus · Accepted Answer

Rounding is when we make a number "simpler" but keep the value as close to the original number as possible. To round a number:
Determine which digit or place (value) is the number you want to "round to." All numbers after this (to the right) will become zeroes after rounding.
Keep it the same number if the next number (the number to its right) is less than 5. Then, change all other numbers to the right to 0. For example, 132 rounded to the nearest ten would be 130. (132 is closer to 130 than it is to 140.)
Increase the number by 1 if the next number (the number to its right) is 5 or more. Then, change all other numbers to the right to 0. For example, 158 rounded to the nearest hundred would be 200. (158 is closer to 200 than it is to 100.)
This question tells us that the length of a straw rounded to the nearest tenth of a cm is 19.7 cm. The two numbers with the highest next digit are 19.74 and 19.75.
Round each to the tenths place:
19.74 → 19.7
19.75 → 19.8
The highest the next digit (the hundredths place) can be and still round down to 19.7 cm is 19.74 cm.
19.75 is incorrect because, according to the rounding rules explained above, it would round up to 19.8, not down to 19.7.
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The Length of a Straw Is 19