This handy Spectrum Math Grade 4 Answer Key Chapter 9 Pretest provides detailed answers for the workbook questions.

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Complete the number patterns.

Question 1.
a. 2, 3, 5, 2, , , 2, 3, 5, 2, , , Explanation:
As it is said that it is a number pattern, so the question follows the pattern 2,3,5 and so on. As the number of the pattern ended in the question is 2, the next numbers would be 3,5 and 2 again.

b. 20, 30, 10, 40, 20, , , 20, 30, 10, 40, 20, , , Explanation:
As it is said that it is a number pattern, so the question follows the pattern 20, 30, 10, 40 and so on. As the number of the pattern ended in the question is 20, the next numbers would be 30 ,10 and 40 again.

Question 2.
a. 75, 50, 25, 10, 75, , , 75, 50, 25, 10, 75, , , Explanation:
As it is said that it is a number pattern, so the question follows the pattern 75, 50, 25, 10 and so on. As the number of the pattern ended in the question is 75, the next numbers would be 50, 25 and 10 again.

b. 1, 3, 5, 1, 3, , , 1, 3, 5, 1, 3, , , Explanation:
As it is said that it is a number pattern, so the question follows the pattern 1, 3, 5 and so on. As the number of the pattern ended in the question is 3, the next numbers would be 5, 1 and 3 again.

Determine the number patterns and complete.

Question 3.
a. 5, 10, 15, 20, , , 5, 10, 15, 20, , , Explanation:
By looking at the given numbers, it’s been noticed that the difference between two consecutive numbers is 5. So, the last number in the given sequence in the question is 20 and so the required next number in the sequence is 20 + 5 = 25. The next number in the sequence should be 25 + 5 = 30. The last number in the sequence is 30 + 5 = 35.

b. 510, 508, 506, , , 510, 508, 506, , , Explanation:
By looking at the given numbers, it’s been noticed that the difference between two consecutive numbers is 2. So, the last number in the given sequence in the question is 506 and so the required next number in the sequence is 506 – 2 = 504. The next number in the sequence should be 504 – 2 = 502. The last number in the sequence is 502 – 2 = 500.

Question 4.
a. 4, 8, 16, 32, , , 4, 8, 16, 32, , , Explanation:
By looking at the given numbers, it’s been noticed that a number is doubled to get another number. So, the last number in the given sequence in the question is 32. Double of 32 is 64 which comes next to 32. Double of 64 is 128 which comes next to 64. The required next number in the sequence is double of 128 which is 256.

b. 78, 87, 99, 114, , 153, 78, 87, 99, 114, , 153, Explanation:
By looking at the given numbers, it’s been noticed that the difference between first two numbers is 9. The difference between second and third numbers is 12. We’ve noticed that difference between two consecutive numbers is increasing by three from there onwards. So, last number in the given sequence in the question is 114 and the difference between 114 and the number before it (99) is 15. So, 18 should be added to the last number 114 to get the next number in the sequence. So, the next number in the sequence is 114+18=132. To get the last number in the sequence 24 should be added to get the next number in the sequence and it will be 153 + 24 = 177.

Complete the geometric patterns.

Question 5.
a.  Explanation:
As it is said that it is a geometric pattern, so the question follows the pattern circle, square, triangle and so on. As the geometric of the pattern ended in the question is circle, the next geometric pattern would be square, triangle and circle again.

b.  Explanation:
As it is said that it is a geometric pattern, so the question follows the pattern two rhombus, two hexagons, two circles and so on. As the geometric of the pattern ended in the question is rhombus, the next geometric pattern would be rhombus hexagon and hexagon again.

Question 6.
a.    