Answer :
To add 382 and 115 mentally, one effective method is to break apart the number 115 into parts that are easy to work with. Let's examine the options given:
1. Option (A) suggests breaking apart 115 into [tex]$8+100+7$[/tex].
2. Option (B) suggests breaking apart 115 into [tex]$10+5$[/tex].
3. Option (C) suggests adding the hundreds, 300 and 100.
4. Option (D) suggests adding the tens first.
Now, let's look at which option makes the calculation simpler:
- Option (A) isn't broken down in a convenient way.
- Option (B) breaks 115 into smaller, simpler parts ([tex]$10+5$[/tex]), which is helpful for quick mental addition.
Here's how you can add 382 and 115 using a simple mental method:
1. Break apart 115 into 100, 10, and 5:
- First, add the large component: [tex]\(382 + 100 = 482\)[/tex].
- Next, add the remaining 10: [tex]\(482 + 10 = 492\)[/tex].
- Finally, add 5: [tex]\(492 + 5 = 497\)[/tex].
The sum is 497. So, the most efficient way to perform this calculation mentally is by using an adjusted version of Option (B) with components 100, 10, and 5.
1. Option (A) suggests breaking apart 115 into [tex]$8+100+7$[/tex].
2. Option (B) suggests breaking apart 115 into [tex]$10+5$[/tex].
3. Option (C) suggests adding the hundreds, 300 and 100.
4. Option (D) suggests adding the tens first.
Now, let's look at which option makes the calculation simpler:
- Option (A) isn't broken down in a convenient way.
- Option (B) breaks 115 into smaller, simpler parts ([tex]$10+5$[/tex]), which is helpful for quick mental addition.
Here's how you can add 382 and 115 using a simple mental method:
1. Break apart 115 into 100, 10, and 5:
- First, add the large component: [tex]\(382 + 100 = 482\)[/tex].
- Next, add the remaining 10: [tex]\(482 + 10 = 492\)[/tex].
- Finally, add 5: [tex]\(492 + 5 = 497\)[/tex].
The sum is 497. So, the most efficient way to perform this calculation mentally is by using an adjusted version of Option (B) with components 100, 10, and 5.
