Which of the following expressions correctly use mental math to find ? Select all that
apply.
(1 point)
4 × 59 4 × 59
(4 × 60) − (4 × 1) ( 4 × 60) - ( 4 × 1)
4 × (50 × 9) 4 × ( 50 × 9)
4 + (50 × 9) 4 + ( 50 × 9)
(4 × 50) + (4 × 9) ( 4 × 50) + ( 4 × 9)
4 + 50 + 9
To determine which of the expressions correctly use mental math to find the answer, let's analyze each option:
1) 4 × 59: This expression does not involve mental math since you directly multiply 4 and 59.
2) (4 × 60) − (4 × 1): This expression can be simplified using mental math. By recognizing that multiplying 4 by 60 is the same as multiplying it by 6 and adding a zero at the end, we have (4 × 10) - (4 × 1). Then, we can calculate mentally: 40 - 4 = 36.
3) 4 × (50 × 9): This expression can be simplified using mental math. By recognizing that 50 × 9 can be rewritten as 50 × 10 - 50, we have 4 × (500 - 50). Then, we can calculate mentally: 4 × 450 = 1800.
4) 4 + (50 × 9): This expression does not involve mental math since you directly multiply 50 and 9 and then add 4.
5) (4 × 50) + (4 × 9): This expression can be simplified using mental math. By recognizing that 4 × 50 is the same as multiplying it by 5 and adding a zero at the end, we have (4 × 5) + (4 × 9). Then, we can calculate mentally: 20 + 36 = 56.
6) 4 + 50 + 9: This expression does not involve mental math since you directly add 4, 50, and 9.
Based on our analysis, the expressions that correctly use mental math to find the answer are options 2), 3), and 5).
The expressions that correctly use mental math to find the answer are:
(4 × 59) - This can be calculated by multiplying 4 by 50 (200) and adding 4 times 9 (36), which equals 236.
(4 × 59) - This can also be calculated by multiplying 4 by 60 (240) and subtracting 4 (236).
(4 × 60) - (4 × 1) - This can be calculated by multiplying 4 by 60 (240) and subtracting 4 (236).
4 × (50 × 9) - This can be calculated by multiplying 50 by 9 (450) and then multiplying the result by 4, which equals 1800.
(4 × 50) + (4 × 9) - This can be calculated by multiplying 4 by 50 (200) and adding 4 times 9 (36), which equals 236.
4 + 50 + 9 - This can be calculated by adding 4, 50, and 9, which equals 63.
The expressions that correctly use mental math to find the result are:
- (4 × 60) − (4 × 1)
- 4 × (50 × 9)
- 4 + (50 × 9)
- (4 × 50) + (4 × 9)
These expressions involve simple calculations that can be done mentally without the need for a calculator or written work.