The value highlighted in yellow located in the upper right corner (in the diagram above) represents the last three digits of the observed pressure reading in millibars (mb).
If the first digit of the pressure report is greater than "5", then place a "9" in front of the value given. Then, add a decimal point before the last digit. Therefore, if the number found in the upper right corner is 943, the reported pressure is actually 994.3 mb.
If the first digit of the pressure report is less than "5", then place a "10" in front of the value given. Then, add a decimal point before the last digit. Therefore, if the number found in the upper right corner is 298, the reported pressure is actually 1029.8 mb.
In the example depicted above, the highlighted pressure value is 027. Therefore, since the first digit of "027" is less than "5", a "10" is placed in front of "027" and a decimal point before the last digit, which is a "7". This gives us an actual pressure report of 1002.7 mb.