The attacks, which wounded dozens, come as Iraq witnesses its worst violence since 2008, a surge in bloodshed that has killed more than 5,400 people this year despite authorities having carried out a swathe of operations and implemented tightened security measures.
They struck as Prime Minister Nuri al-Maliki visits Washington to press for military equipment and greater cooperation with the United States in fighting militants.
In today's deadliest attack, twin car bombs in a residential area in Tuz Khurmatu, a disputed town north of Baghdad, killed seven people and wounded 42 others.
As emergency responders rushed to the scene of the attack, a third bomb went off, but did not cause any casualties, Mayor Shallal Abdul told AFP.
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"The two car bombs went off simultaneously, and bear the fingerprints of Al-Qaeda," a police major, who spoke on condition of anonymity, told AFP.
Tuz Khurmatu is a majority Kurdish town which lies in a disputed area of northern Iraq, where both Iraq's autonomous Kurdish region and the central government in Baghdad vie for power.
It is frequently hit by deadly attacks.
Two more near-simultaneous car bombs went off in Khales, a restive town north of Baghdad, as a police patrol was passing, killing five people, including a policeman, officials said.
Another car bomb in Muqdadiyah, north of Baghdad, killed four people.
Police meanwhile found the bodies of three blindfolded women bearing multiple gunshot wounds to the head, execution-style, at an empty plot in a Shiite-majority neighbourhood in northeast Baghdad.
A police officer and a medical official said initial investigations showed the women were shot earlier today.
Also today, gunmen killed a soldier and wounded two others in an attack targeting their patrol in the northern city of Mosul, while a roadside bomb targeting an army patrol northwest of the city left a soldier dead and two others wounded, officials said.