Why is sum of series coming as fractional and less than the actual values in graphite

Question

I am creating a dashboard using metrics in graphite. I have tried consolidatedBy to get all the metrics. The metric values looks correct and are of the range of 1000s.

The graphite query for the same is

consolidateBy(monitors.x.y.z.client_metrics.k.*.*.*.*.*.response_codes.*.count, 'sum')

I want to get the total number of requests, which would be sum of all this series. So, I tried the sum function but it is giving the sum around 1-12, which is actually less than the actual values.

The query is

sum(consolidateBy(monitors.x.y.z.client_metrics.k.*.*.*.*.*.response_codes.*.count, 'sum'))

This query also gives the same result

sum(monitors.x.y.z.client_metrics.k.*.*.*.*.*.response_codes.*.count)

My questions are:

1. Why is the sum of series giving point's value less than the actual values ?
2. I just want to calculate the total number of requests. If there is an easier solution. Can you please specify it.