1. WLTP-23-04e_Appendix15
Rounding
IWG # 23
Geneva, June 2018

2. WLTP GTR
The term rounding is used frequently in GTR 15. Based on ASTM standard E29-13 and ISO standard 17025, this is an attempt to prescribe rules to round a result up or not.

3. WLTP GTR
Rule 1:
When the digit immediately to the right of the last place to be retained is less than 5, that digit shall remain unchanged.
EXAMPLE:
If a result is grams but only two places of decimal are to be retained, the final result shall be 1.23 grams.

4. WLTP GTR
Rule 2:
When the digit immediately to the right of the last place to be retained is greater than 5, that digit shall be increased by 1.
EXAMPLE:
If a result is grams but only two places of decimal are to be retained, and because 6 is greater than 5, the final result shall be 1.24 grams.

5. WLTP GTR
Rule 3:
When the digit immediately to the right of the last place to be retained is 5 and all the following digits are zero, the last digit to be retained shall be increased by 1 if it is odd or shall remain unchanged if it is even. Note that this means the final digit is always even.
EXAMPLES:
If a result is grams and the following digits are zero but only two places of decimal are to be retained, and because 3 is odd, the final result shall be 1.24 grams.
If a result is grams and the following digits are zero but only two places of decimal are to be retained, and because 4 is even, the final result shall be 1.24 grams.

6. WLTP GTR
Rule 4:
When the digit immediately to the right of the last place to be retained is 5 and there are non-zero digits beyond the 5, the last digit to be retained shall be increased by 1.
EXAMPLE:
If a result is grams and only two places of decimal are to be retained, the final result shall be 1.36 grams.

7. WLTP GTR
Where the term rounding or rounded is used in GTR 15, the corresponding sentence has been modified to include a reference to paragraph 7 as, for example, "Rounding according to paragraph 7. of this UN GTR".

8. END