1. How long did it take him to read the book?

2. How long did it take for him to read the book?
(Are both grammatical?)

3. It took him five days to read the book.
4. It took him 5 days to read the book.
(Which one is commonly used?)

1 & 2 are both correct. We probably would not say, "for him to read", but it is correct. We would just say, "How long did it take him..."

3 & 4. 3 is correct. 4 is not. Any number up to eleven is spelled out, "five", not "5". At the beginning of a sentence, a number is spelled out, but numbers above 12 may be expressed in numerals within the sentence.

"One hundred years ago, people still used the horse and buggy to travel from place to place."

"It only took ten minutes to eat our lunch."

"The war in Korea began 66 years ago, in 1950."

"He is 26 years old."

"Twenty-six years ago, I started my first job."

The two figures shown below are congruent. Identify the corresponding sides and angles.

The two figures shown below are congruent. Identify the corresponding sides and angles.

The two figures shown below are congruent. Identify the corresponding sides and angles.

The two figures shown below are congruent. Identify the corresponding sides and angles.

1. Both sentences, "How long did it take him to read the book?" and "How long did it take for him to read the book?" are grammatically correct.

2. Both sentences convey the same meaning, but there is a slight difference in their structure. Sentence 1 uses the preposition "to" followed by the verb "read," while Sentence 2 uses the preposition "for" followed by the pronoun "him" and the verb "to read." In practical usage, Sentence 1 is more commonly used.

3. Sentence 3, "It took him five days to read the book," is more commonly used. This sentence states the duration it took for him to read the book directly and precisely.

4. Sentence 4, "It took him 5 days to read the book," is also grammatically correct and conveys the same meaning as Sentence 3. However, Sentence 4 uses the numeral "5" instead of writing out the word "five" as in Sentence 3. Both expressions are acceptable, but in writing, it is generally preferred to use the word form (five) rather than the numeral form (5) for whole numbers.