@mhdevx - we discussed this problem before here:
Posting non-string data to Parse.com using Webhook
I have exactly the same issue - cannot post numbers, can only post strings using webhooks. Easiest way is to have a proxy hop in-between PHP / Node that converts strings to numbers before posting to Parse.com.
This is a known limitation in the way Particle web hooks are implemented. @Dave commented on this in an different discussion.