Most of these have targeted police or security forces, government officials or commuters going to work in the morning.
The simultaneous bombs tactic has been much used by Iraqi insurgents since the US-led invasion in 2003, says the BBC's Andrew North in Baghdad.
There are suspicions that the blasts were an al-Qaeda attempt to re-ignite sectarian conflict in Baghdad, says our correspondent. Kasra adjoins the mainly-Sunni district of Adhamiya.
A minibus full of schoolgirls was caught in the attack. Television pictures showed blood on the seats and girls shoes scattered in the wreckage.
Shop fronts were torn apart and debris was strewn across the street.
"We are fed up with such attacks and we want only to live in peace," said local grocery store owner Ahmed Riyadh.
Baghdad was torn by sectarian strife through 2006-7, but it has since largely subsided as many local militias have joined Awakening Councils set up by the US forces. Smaller attacks still take place on a daily basis, however.
The suicide car bomber in Baquba, in Diyala province, struck a checkpoint staffed by a local Awakening Council militia.
Six militia members were killed and 14 civilians were wounded, police said.
The US military began transferring control of the Awakening Council militias to the Iraqis on 1 October and on Monday the government started paying the salaries of the Baghdad councils.
The Awakening Council militias, along with the increase in US troop numbers, are credited with the dramatic improvements in security in Iraq since the fierce sectarian violence of 2006-7.
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