Write three hundred twelve and eight thousand nine hundred seventy-eight ten-thousandths as a decimal number.
The given number, three hundred twelve and eight thousand nine hundred seventy-eight ten-thousandths, can be written as:
312 + 0.8978
To write this sum as a decimal number, we can add the whole numbers and the decimal portions separately:
312.0000 + 0.8978
Simplifying the sum, we find:
312.8978
Therefore, three hundred twelve and eight thousand nine hundred seventy-eight ten-thousandths can be written as the decimal number 312.8978.