A 3rd standard student, when asked to write one hundred and five in numeral form, s/he writes it as '1005'. This indicates that :

The correct answer is: s/he needs more help in understanding the concept of place value

Explanation:
When a student writes "one hundred and five" as 1005 instead of 105, it shows a misconception regarding the base-ten place value system.

1. Breakdown of the number:
"One hundred and five" consists of:
- 1 hundred (100)
- 0 tens (00)
- 5 ones (5)

2. Student's Misconception:
The student writes "100" for "one hundred" and places "5" right next to it, producing "1005" (which is actually one thousand and five). This indicates that the child is writing the numbers phonetically as they hear them (100 and 5 concatenated), rather than combining the values into their proper positional columns (Hundreds, Tens, Ones).

Therefore, this common error highlights that the student needs further guidance and practice in understanding how place values combine to form numbers.