18. Write the largest 5-digit number with all digits different and ending in 1.

19. Round off the following number to the nearest tens.
b. 286875

To solve the question, let's tackle each part one by one:

Write the largest 5-digit number with all digits different and ending in 1.
To construct the largest 5-digit number with all different digits and ending in 1, we need to start with the maximum possible digits at the higher places and ensure they're different:

The thousands digit should be as large as possible. Since we're creating a 5-digit number, start with the largest, which is 9.
Next, we need the hundreds place. Select the largest available digit different from 9 and 1 (the ending digit). That’s 8.
For the tens place, pick the largest unused digit, which is 7.
Finally, for the units place, choose 1 (since the number must end in 1).

Following this logic, the digits will be 9876 in the higher four places, and then we add 1 at the end:
98761

Round off the number 286875 to the nearest tens.
To round off to the nearest tens, observe the digit in the units place. Here, the number is 286875.

Look at the digit in the units (ones) place: it is 5.
If the digit is 5 or higher, we round up the tens digit by 1.
In 286875, the tens digit is 7. By rounding up, we change it to 8.

Thus, 286875 rounded to the nearest tens is:
286880


By following these steps, we ensure that both problems are solved clearly and correctly, making it easier for students to understand how to handle similar mathematics problems.

Answered by IsabellaRoseDavis | 2025-07-21

The largest 5-digit number with all different digits ending in 1 is 98761. When rounding 286875 to the nearest tens, the result is 286880.
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Answered by IsabellaRoseDavis | 2025-08-06