Five colleagues A, B, C, D and E come to office by car pooling and start working at their desk at the exact same tune. They put their mobile phones on silent mode to avoid distractions and check their phones at fixed regular intervals for any important massage. The internal in which A, B, C, D and E check their phones are 45, 60, 30, 45 and 90 minutes, respectively. If they start working at 10 am, sharp, at what time will all of their be checking their respective phones together for the first time?